<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h2 id="h2">0</h2>
    <button id="minus">-1</button>
    <button id="add">+1</button>
</body>
<script>
    let minus = document.getElementById("minus");
    let add = document.getElementById('add');
    let h2 = document.getElementById('h2');
    let count = 0
    minus.addEventListener("click", () => {
        count--;
        h2.innerText = count;
    })
    add.addEventListener("click", () => {
        count++;
        h2.innerText = count;
    })
</script>
</html>